She started performing from an early age. She started by acting in several productions of Shakespeare's plays such as Romeo and Juliet and Much Ado About Nothing around her locality in San Francisco Bay. Her co-star in Romeo and Juliet advised her to take acting seriously and seeking his advice Chastain enrolled at the Juilliard School in NYC.
While Chastain was pursuing her last year at Juilliard School, The noted producer of various famous shows, John Wells came to see an acting showcase in the school and saw her performing. He was left numb with her stellar performance and immediately signed her to a one-year contract. She got roles on Wells's famous shows like Dark Shadows, ER and Law & Order: Trial by Jury and a series of several other shows.
She then branched into films and starred in films like Jolene andThe Debt. She won huge appreciation for her performance in the cult classic film Take Shelter in 2011. The biggest hit of her career thus far is the film The Help. For her performance, she also won an Oscar Nomination.
After a highly successful 2011, she was cast in several new projects, including Zero Dark Thirty and Madagascar 3: Europe's Most Wanted. Zero Dark Thirty was directed by noted director Kathryn Bigelow and it was based on the hunt for international terrorist Osama bin Laden. She was cast in the lead role as a CIA operative and for her splendid performance in the film, she won herself Golden Globe Award under the category of best actress in 2013.
Chastain founded her own production company called Freckle Films in the year 2016. She is well-known as an outspoken feminist and actively works for advocating equal rights for women in Hollywood.